Many of non-steroidal anti-inflammatory drugs that have been widely used as antipyretic, analgesic and agents for antiinflammatory (hereinafter referred to as “NSAIDs”) show pharmacologic actions mainly by inhibiting an enzyme called cyclooxygenase. Cyclooxygenase is involved in enormous numbers of pathologic conditions such as pain, fever, chronic and acute inflammation, arthritis, colon cancer, new blood vessel growth, asthma, arterial sclerosis, Alzheimer disease, and Parkinson's disease. Therefore, it has been considered that examining behaviors of NSAIDs within a living body makes it possible to find out many pathologic conditions and diagnoses.
According to the above described reasons, examining behaviors of NSAIDs in the living body by a PET method has been actively tried in recent years. PET is a method that includes administering, into a living body, a tracer labeled with a short-term radionuclide which releases positrons such as 11C or 18F so that γ rays generated from the tracer is measured by a PET camera (detector comprising a gamma ray scintillator and a photoelectron multiplier tube), and imaging a body distribution of the γ ray by a computer. The PET method can non-invasively and quantitatively track down behaviors of medical agents in living bodies including from small animals to a human and a degree of reaching a target site. NSAIDs such as ibuprofen and naproxen inhibit functions of an enzyme called cyclooxygenase in a living body to show anti-inflammatory actions, and it was found that cyclooxygenase is involved in not only inflammation but also tumors, Alzheimer disease, and the like. Therefore, in order to apply NSAIDs to a PET method, numerous NSAIDs have been labeled with 11C and 18F (Non-Patent Documents 1 to 15). Analyzing PET images for NSAIDs enables non-invasive imaging of cyclooxygenase, and consequently, significantly useful information can be obtained in respective fields such as biology, development of pharmaceutical products, and medical services.